Abstract: An optical member of lighting device is revealed. The optical member consists at least one emergent surface that is a spherical surface or an aspherical surface, and at least one incident surface with a V-shaped groove or a V-shaped like groove. The V-shaped groove is formed by two symmetrical or asymmetrical slants while the V-shaped like groove is formed by a plurality of curves. Moreover, axes of the emergent surface and the incident surface can be overlapped, shift relatively, slanted relatively to each other or combinations of them. When the optical member is used in combination with at least one solid state lighting element, an asymmetrical batwing light distribution pattern that features on non-zero maximum light intensity is generated. Thus the area being emitted is with uniform luminance and the availability of light is improved.